Accessing method and apparatus for use in hybrid optical recording device

ABSTRACT

A disc apparatus comprising: an optical pick-up 5 that accesses an optical disc 4 adapted so that the area on the disc is divided into at least one reproduction only area and one recordable area, and information indicating boundary recording track position between the reproduction only area and the adjacent recordable area is recorded; a sled motor 11 that moves the optical pick-up 5 along the radius of the disc; an RF amplifier 7 that generates a traverse signal from a reproduction signal obtained by the optical pick-up 5, which signal level changes every time the optical pick-up 5 traverses the recording tracks at a first setting corresponding to the reproduction only area and a second setting corresponding to the recordable area selected on the basis of a switching signal when the optical pick-up 5 is being moved; a servo circuit that counts, based on the traverse signal, the number of recording tracks over which the optical pick-up 5 has been moved; and a system controller 8 that, when the boundary recording track position exists between the detected current recording track position accessed by the optical pickup 5, and the target recording track position, it outputs the switching signal to the RF amplifier 7 based on the number of movement recording tracks that are detected by a detector of the number of movement recording tracks and that are counted by the servo circuit 9.

TECHNICAL FIELD

This invention relates to a disc apparatus and a disc access method foraccessing a disc-shaped recording medium including the reproduction(playback) only area and the recordable/reproducible area.

BACKGROUND ART

Hitherto, as the disc-shaped recording medium, reproduction (playback)only disc such as digital audio disc including the reproduction(playback) only area in which data are recorded by pits, etc.,recording/reproduction disc including the recordable area for data bythe magnetic recording film or the magneto-optical recording film,hybrid disc including the reproduction only area in which data arerecorded by pits and the recordable area for data by the magneto-opticalrecording film, and the like are known.

In the hybrid disc, management information for carrying out managementof data recorded in the reproduction only area is recorded in thereproduction only area to carry out management of data in thereproduction only area on the basis of the management informationreproduced from the reproduction only area. Moreover, managementinformation for carrying out management of data recorded in therecordable area is recorded in the recordable area to carry outmanagement of data recorded in the recordable area on the basis of themanagement information reproduced from the recordable area.

For example, in the optical disc, there is a hybrid type optical disc inwhich the information recording surface is divided so that thereproduction only area and the recordable/reproducible area are formed.The optical disc apparatus to which such hybrid type optical disc isapplied is adapted so that desired data can be reproduced by thereproduction systems corresponding to respective areas, and desired datacan be recorded by the recording/reproduction system corresponding tothe recordable area.

Namely, in this hybrid type optical disc, the area of the innercircumferential side is allocated (assigned) to the reproduction onlyarea, and predetermined data are recorded in advance in this area bypits similar to those of the digital audio disc. On the contrary, thearea of the outer circumferential side is allocated (assigned) to therecordable/reproducible area, and the perpendicular magnetization filmis formed therein.

Thus, in the optical disc apparatuses of this kind, processing ofrecording/reproduction is executed in the reproduction only area and therecordable/reproducible area by technique similar to those employed inthe digital audio disc player and the magneto-optical disc apparatus.

Moreover, in the case of carrying out seek operation across thereproduction only area and the recordable/reproducible area, the opticaldisc apparatuses of this kind are adapted to detect position of theoptical pick-up by the position detecting sensor disposed in the movable(moving) direction of the optical pick-up, or to detect position of theoptical pick-up by the number of drive pulses of the stepping motor forallowing the optical pick-up to undergo seek operation, thus to allowthe optical pick-up to undergo seek operation (positioning onto adesignated track).

Thus, in the optical disc apparatuses of this kind, switching of theentire operation is carried out in correspondence with two areas ofwhich reproduction systems are different, thus making it possible tocarry out recording/reproduction of desired data.

Meanwhile, if the position detecting sensor of the optical pick-up canbe omitted in the optical disc apparatuses of this kind, the entireconfiguration can be simplified accordingly. Further, at this time, ifthe optical pick-up is caused to undergo seek operation by the d.c.motor in place of the stepping motor, the entire configuration can besimplified to still more degree.

However, in the conventional optical disc apparatuses, in the case wherethe position detecting sensor is omitted and the optical pick-up iscaused to undergo seek operation by the d.c. motor as stated above, itbecomes difficult to directly detect position of the optical pick-upduring seek operation.

In this case, there is proposed a method of detecting change ofreproduction signal, etc. obtained by the optical pick-up to therebydetect movement quantity of the optical pick-up to thereby roughlydetect the position of the optical pick-up.

In practice, however, there are instances where seek operation may becarried out in the state where the optical pick-up passes across theboundary between two areas. In this case, it becomes difficult toprecisely detect the movement quantity. For this reason, in the casewhere seek operation is carried out over the long distance across theboundary, there results the fact that the optical pick-up is caused toundergo seek operation so that it is located at the position caused toundergo displacement to much degree from the seek target (objective).

Moreover, in this case, the operation of the servo circuit would not becorrectly set in correspondence with respective areas. As a result, theservo circuit is held in the unstable state. There are instances whereoptical pick-up might run away.

In this connection, also in the recordable/reproducible optical disc,there also exist optical discs in which the reproduction only area isformed by pits in the small area of the inner circumferential side torecord management information by using the small area as the lead-inarea. In this case, because the lead-in area is the small area and themovement speed of the optical pick-up traversing the boundary is causedto be low, such a problem does not take place.

This invention has been made in view of circumstances as describedabove, and its object is to provide a disc apparatus and a disc accessmethod which are capable of stably and securely accessing a desired areaby simple configuration with respect to a disc-shaped recording mediumin which the information recording surface is divided into areas ofdifferent reproduction systems.

DISCLOSURE OF THE INVENTION

This invention is directed to a disc apparatus for accessing adisc-shaped recording medium including recording tracks in a spiral formor in a concentrical form, and being such that the area thereon isdivided into at least one reproduction only area and one recordable areaevery predetermined position in a radial direction, and that boundaryrecording track position information indicating a boundary recordingtrack position between the reproduction only area and the recordablearea which are adjacent to each other is recorded, the apparatuscomprising: a head for providing an access to the disc-shaped recordingmedium; head movement means for moving the head in the radial directionof the disc-shaped recording medium; current position detecting meansfor detecting a recording track position that the head is accessing atpresent to output current position information indicating the currentrecording track position; means for detecting the number of movementrecording tracks, which is operative to detect, on the basis of targetrecording track position information indicating a target recording trackposition, the current position information and the boundary recordingtrack position information, the number of movement recording tracks fromthe current recording track position up to the boundary recording trackposition when the boundary recording track position indicated by theboundary recording track position information exists between the currentrecording track position indicated by the current position informationand the target recording track position indicated by the targetrecording track position information; traverse signal generating meansoperative to generate, from a reproduction signal obtained by the head,a traverse signal of which signal level changes every time the headtraverses the recording tracks at a first setting corresponding to thereproduction only area or a second setting corresponding to therecordable area selected on the basis of a switching signal when thehead is being moved by the head movement means; count means forcounting, on the basis of the traverse signal, the number of recordingtracks over which the head has been moved; and switching signalgenerating means for outputting the switching signal to the traversesignal generating means on the basis of the number of movement recordingtracks detected by the means for detecting the number of movementrecording tracks and the number of recording tracks counted by the countmeans.

Moreover, this invention is directed to a disc apparatus for accessing adisc-shaped recording medium including recording tracks in a spiral formor in a concentrical form, and being such that the area thereon isdivided into at least one reproduction only area and one recordable areaevery position in a radial direction, and that boundary recording trackposition information indicating a boundary recording track positionbetween the reproduction only area and the recordable area which areadjacent to each other is recorded, the apparatus comprising: a head forproviding an access to the disc-shaped recording medium; head movementmeans for moving the head in the radial direction of the disc-shapedrecording medium; current position detecting means for detecting arecording track position that the head is accessing at present to outputcurrent position information indicating the current recording trackposition; boundary detecting means for detecting, on the basis of targetrecording track position information indicating a target recording trackposition, the current position information and the boundary recordingtrack position information, whether or not the boundary recording trackposition indicated by the boundary recording track position informationexists between the current recording track position indicated by thecurrent position information and the target recording track positionindicated by the target recording track position information; means fordetecting the number of movement recording tracks, which is operative sothat when it is detected by the boundary detecting means that theboundary recording track position exist, the detecting means detects thenumber of the movement recording tracks from the current recording trackposition up to a recording track position spaced by a predeterminednumber of recording tracks from the boundary recording track position;traverse signal generating means operative to generate, from areproduction signal obtained by the head, a traverse signal of whichsignal level changes every time the head traverses the recording tracksat a first setting corresponding to the reproduction only area or asecond setting corresponding to the recordable area selected on thebasis of a switching signal when the head is being moved by the headmovement means; count means for counting, on the basis of the traversesignal, the number of recording tracks over which the head has beenmoved; area detecting means for detecting, on the basis of areproduction signal obtained by the head, whether an area that the headis positioned is the reproduction only area or the recordable area; andcontrol means for carrying out a first operation to move the head towardthe boundary recording track position by the head movement means,whereby when the number of recording tracks counted by the count meansbecomes in correspondence with the number of movement recording tracksdetected by the means for detecting the number of movement recordingtracks, the control means stops movement of the head by the headmovement means to output, to the traverse signal generating means, theswitching signal corresponding to an area detection signal by the areadetecting means in the state where the head is stopped.

In the disc apparatus according to this invention, the control means isoperative subsequently to the first operation, for example, to detect,on the basis of the area detection signal by the area detecting means,whether or not the head has reached the boundary recording trackposition, whereby when the head does not reach the boundary recordingtrack position, the control means further moves the head by the headmovement means by the time determined on the basis of current positioninformation obtained by the current position detecting means and thetarget recording track position information. In addition, the headincludes, e.g., light beam irradiation means for irradiating light beamsonto the disc-shaped recording medium, and plural detectors fordetecting ray of reflected light from the disc-shaped recording medium.

In the disc apparatus according to this invention, the traverse signalgenerating means includes, e.g., operation processing means forperforming an operation with respect to output signals of the pluraldetectors by a first operational expression corresponding to thereproduction only area or a second operational expression correspondingto the recordable area selected on the basis of the switching signal. Inaddition, the traverse signal generating means includes, e.g.,amplifying means for amplifying an output signal of the head by a firstgain corresponding to the reproduction only area or a second gaincorresponding to the recordable area selected on the basis of theswitching signal. The amplifying means amplifies an output signal of thehead by the first gain smaller than the second gain.

In addition, the traverse signal generating means includes band limitingmeans for limiting the band of an output signal of the head at a firstfrequency band corresponding to the reproduction only area or a secondfrequency band corresponding to the recordable area selected on thebasis of the switching signal. The band limiting means limits the bandof an output signal of the head at the first frequency band narrowerthan the second frequency band.

In the disc apparatus according to this invention, the switching signalgenerating means is operative so that when, e.g., the number of movementrecording tracks detected by the means for detecting the number ofmovement recording tracks and the number of recording tracks counted bythe count means are in correspondence with each other, the switchingsignal generating means outputs the switching signal to the traversesignal generating means.

The disc apparatus according to this invention is adapted so that, e.g.,the boundary recording track position information is recorded on therecording track of the disc-shaped recording medium, whereby therecording track where the boundary recording track position informationis recorded is accessed by the head to read out the boundary recordingtrack position information.

The disc apparatus according to this invention is operative to accessthe disc-shaped recording medium accommodated within a cartridgeprovided with memory means in which the boundary recording trackposition information is stored.

The disc apparatus according to this invention further includes, e.g.,read-out means for reading out the boundary recording track positioninformation from the memory means.

In the disc apparatus according to this invention, the operationalprocessing means performs an operation with respect to output signals ofthe plural detectors by a first operational expression for generating areproduction signal from the reproduction only area in which therecording tracks are formed by pits, or a second operational expressionfor generating a tracking error signal from the recordable area in whichthe recording tracks are formed by grooves.

This invention is directed to a disc access method for accessing, bymoving a head in a radial direction of a disc-shaped recording medium,the disc-shaped recording medium including recording tracks in a spiralform or in a concentrical form, and being such that the area thereon isdivided into at least one reproduction only area and one recordable areaevery predetermined position in the radial direction thereof, and thatboundary recording track position information indicating a boundaryrecording track position between the reproduction only area and therecordable area which are adjacent to each other is recorded, the methodcomprising the steps of: reading the boundary recording track positioninformation recorded on the disc-shaped recording medium; detecting acurrent recording track position that the head is accessing at present;detecting, on the basis of the detected current recording trackposition, a target recording track position and boundary recording trackposition indicated by the boundary recording track position information,the number of movement recording tracks from the current recording trackposition up to the boundary recording track position when the boundaryrecording track position exists between the current recording trackposition and the target recording track position; generating, from areproduction signal obtained by the head, a traverse signal of whichsignal level changes every time the head traverses the recording tracksat a first setting corresponding to the reproduction only area or asecond setting corresponding to the recordable area selected on thebasis of a switching signal when the head is being moved; counting, onthe basis of the traverse signal, the number of recording tracks overwhich the head has been moved; and outputting the switching signal onthe basis of the number of movement recording tracks and the countednumber of recording tracks. In accordance with the disc access methodaccording to this invention, when, e.g., the number of movementrecording tracks and the counted number of recording tracks are incorrespondence with each other, the switching signal is outputted to thetraverse signal generating means.

This invention is directed to a disc access method for accessing, bymoving a head in a radial direction of the disc-shaped recording medium,the disc-shaped recording medium including recording tracks in a spiralform or in a concentrical form, and being such that the area thereon isdivided into at least one reproduction only area and one recordablearea, and that boundary recording track position information indicatinga boundary recording track position between the reproduction only areaand the recordable area which are adjacent to each other is recorded,the method comprising the steps of: reading the boundary recording trackposition information recorded on the disc-shaped recording medium;detecting a current recording track position that the head is accessingat present; detecting, on the basis of the detected current recordingtrack position, a target recording track position and the boundaryrecording track position indicated by the boundary recording trackposition information, the number of movement recording tracks from thecurrent recording track position up to a recording track position spacedby a predetermined number of recording tracks from the boundaryrecording track position when the boundary recording track positionexists between the current recording track position and the targetrecording track position; generating, from a reproduction signalobtained by the head, a traverse signal of which signal level changesevery time the head traverses the recording tracks at a first settingcorresponding to the reproduction only area and a second settingcorresponding to the recordable area selected on the basis of aswitching signal when the head is being moved; moving the head towardthe boundary recording track position; counting, on the basis of thetraverse signal, the number of recording tracks over which the head hasbeen moved; stopping movement of the head when the counted number ofrecording tracks becomes in correspondence with the detected number ofmovement recording tracks; detecting, on the basis of a reproductionsignal by the head, in the state where the head is stopped, whether anarea where the head is positioned is the reproduction only area and therecordable area; and outputting the switching signal in dependency uponthe detection result thus obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of a firstembodiment of an optical disc apparatus according to this invention.

FIG. 2 is a plan view showing, in a model form, the area configurationof the hybrid type optical disc.

FIG. 3 is a view showing the sector configuration of optical disc loadedinto the optical disc apparatus.

FIG. 4 is a view showing the content of TOC sector=0 of lead-in area ofthe optical disc.

FIG. 5 a perspective view showing the configuration of optical pick-upin the optical disc apparatus.

FIG. 6 is a plan view showing, in a model form, the structure of lightreceiving surface of light receiving element in the optical pick-up.

FIG. 7 is a circuit diagram showing the configuration of the essentialpart of RF amplifier in the optical disc apparatus.

FIG. 8 is a circuit diagram showing another configuration of theessential part of the RF amplifier.

FIG. 9 is a circuit diagram showing a further configuration of theessential part of the RF amplifier.

FIG. 10 is a flowchart showing processing procedure by system controllerin the optical disc apparatus.

FIG. 11 is a flowchart showing processing procedure by the systemcontroller.

FIG. 12 is a block diagram showing the configuration of a secondembodiment of the optical disc apparatus according to this invention.

FIG. 13 is a flowchart showing processing procedure by system controllerin the second embodiment.

FIG. 14 is a block diagram showing the configuration of a furtherembodiment of the optical disc apparatus according to this invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of this invention will now be described in detailwith reference to the attached drawings.

(1) First embodiment

FIG. 1 is a block diagram showing an optical disc apparatus according toan embodiment of this invention. This optical disc apparatus 20 isformed (adapted) so as to have an ability to selectively load thereintoreproduction (playback) only optical disc, disc forrecording/reproduction, or hybrid (type) optical disc, and is operativeto output, to a host computer 2, reproduction data D1 obtained from theoptical disc 4 in response to command outputted from the host computer2, or to record data D2 outputted from the host computer 2 ontocorresponding optical disc 4 in a manner opposite to the above.

Here, the reproduction only optical disc is adapted so that theinformation recording surface is formed by pits similarly to the digitalaudio disc, and the small area of the innermost circumference, the smallarea of the outermost circumference and the intermediate area arerespectively allocated to the lead-in area, the lead-out area and theprogram area. In this program area, data, e.g., computer program, etc.is recorded. Management information (TOC: Table Of Contents) of theprogram area is recorded in the lead-in area.

In the optical disc for recording/reproduction, the lead-in area, UTOC(User Table Of Contents) area, the program area and the lead-out areaare provided (assigned) in order from the inner circumferential side.The lead-in area is formed by pits, and position information of the UTOCarea, etc. is recorded in the lead-in area. Moreover, the UTOC area, theprogram area and the lead-out area are formed by perpendicularmagnetization film so as to have an ability to carry outrecording/reproduction of desired data by applying the thermal magneticrecording technique, and management information of the program area canbe recorded in the UTOC area. Further, in the UTOC area, the programarea and the lead-out area, pregrooves comprised of guide grooves oflaser beam are formed in a meandering manner. They are formed so thatthe tracking control can be conducted with the respective pregroovesbeing as reference. Moreover, meandering of the pregroove is detected torotationally drive the optical disc at a prescribed (specified) rotationvelocity, and to further have ability to detect position information oflaser beam irradiation position.

The hybrid type optical disc is the so-called hybrid disc including areproduction only program area 42 and a recordable program area 45, asshown in FIG. 2, for example, and comprises, from the innermostcircumferential side thereof, a lead-in area 41, the reproduction onlyprogram area 42, a power calibration area 43, a UTOC area 44, therecordable program area 45, and a lead-out area 46.

The lead-in area 41 and the reproduction only program area 42 of theinner circumferential side are formed as the reproduction only area bypits. Moreover, the UTOC area 44, and the recordable program area 45 ofthe outer circumferential side and the lead-out area 46 are formed inthe recordable/reproducible area by the perpendicular magnetization filmsimilarly to the recordable/reproducible optical disc. Thus, therecordable program area 45 can be caused to undergorecording/reproduction in accordance with e.g. the computer program,etc. recorded in the reproduction only program area 42.

In this optical disc 4, as the sector configuration thereof is as shownin FIG. 3, one sector consists of SYNC of 12 bytes which is the fieldfor taking sector synchronization, HEADER of 4 bytes which is the fieldwhere data indicating address and/or mode of sector are stored, and DATAof 2336 bytes which is the actual data field.

Further, in the lead-in area 41, as the content of its TOC sector=0 isas shown in FIG. 4, kind of disc (Disc type), optimum recording power ofdisc (Rec. Power Pwl), start address of the lead-out area (Lead-outstart address), start address of the power calibration area (Power cal.area start address), start address of the recordable area (Recordableuser area start address), pointer indicating start address of track n(n=1˜255) (P-TNO), and start addresses (Start address) and end addresses(End address) of respective tracks, etc. are recorded.

It is to be noted that the track is logical set of data that themanagement system which carries out data management such as managementof recording/reproduction data and/or management of computer file, etc.handles. Moreover, the power calibration area 43 is the area foradjustment of recording power. Further, the UTOC area 44 is the areawhere information with respect to respective tracks within therecordable program area 45 are recorded.

In the optical disc apparatus 20, an optical pick-up 5 and a modulationcoil M are disposed so as to rotationally drive the optical disc 4 thatuser has loaded at a prescribed (specified) rotation velocity by aspindle motor 3, and so that they are opposite to each other in thestate where the optical disc 4 is put therebetween.

In this example, as shown in FIG. 5, for example, the optical pick-up 5emits laser beams of prescribed (specified) plane of polarization from alaser diode 51 included therewithin to converge (focus) these laserbeams onto the information recording surface of the optical disc 4 by anobject lens (objective) 6. Namely, the optical pick-up 5 is adapted(constituted) to move the object lens 6 in upper and lower directionsand in left and right directions so that the focus control and thetracking control can be carried out. This optical pick-up 5 decomposeslaser beams that the laser diode 51 emits into the 0-th order light, the+1-th order light, and the -1-th order light by a diffraction grating 52thereafter to change them into rays of parallel light by a collimatorlens 53 to further guide them to the object lens 6 through a beamsplitter 54 and a 45° mirror 55 to converge main beam by the 0-th orderlight and two sub beams by the +1-th order light and the -1-th orderlight by the object lens 6 to irradiate them onto the informationrecording surface of the optical disc 4. Further, this optical pick-up 5guides rays of return light of the main beam and the respective subbeams irradiated onto the information recording surface of the opticaldisc 4 to a Wollaston prism 56 through the 45° mirror 55 and the beamsplitter 54 to separate respective rays of return light into two beamswhich are in correspondence with the polarization direction and singlebeam which is not in correspondence with the polarization direction bythe Woillaston prism 56 to receive those beams by a light receivingelement 59 through a collimator lens 57 and a multi-lens 58.

As the light receiving surface of the light receiving element 59 is asshown in FIG. 6, in the light receiving element 59 of the opticalpick-up 5, the central light receiving surface in a rectangular form isdivided into areas in matrix form of two rows by two columns so thatrespective light receiving surfaces (represented by symbols A˜D) areformed, and light receiving surfaces in rectangular form (represented bysymbols E, F and I, J) are respectively formed in left and rightdirections and in upper and lower directions of the central lightreceiving surface. The optical pick-up 5 receives rays of return lightof respective sub beams by the +1-th light and the -1-th light of laserbeams on the light receiving surface E and the light receiving surfaceF, respectively. Thus, the optical pick-up 5 can detect tracking errorby applying the so-called three-spot method thereto. Namely, when thereproduction only area formed by pits is reproduced, an approach isemployed to subtract an output signal of the light receiving surface Ffrom an output signal of the light receiving surface E, thereby makingit possible to detect a tracking error signal TE of which signal levelchanges in dependency upon tracking error quantity. The tracking errorsignal TE is detected as E-F when output signals corresponding to thelight receiving surfaces are represented by the same symbol. On thecontrary, in the case where the recordable/reproducible area wherepregrooves are provided are caused to undergo recording/reproduction, anapproach is employed to subtract an output signal of the light receivingsurface E from an output signal of the light receiving surface F,thereby making it possible to detect, as F-E, a tracking error signal TEwhich has the same polarity as that of the tracking error signal TE inthe reproduction only area.

Further, the optical pick-up 5 separates a portion of return light ofthe main beam into the polarization components of 45° by the Wollastonprism 56 to respectively receive them by the light receiving surfaces Iand J. Thus, the optical pick-up 5 adds output signals of the lightreceiving surfaces I and J with respect to return light in thereproduction only area, thereby making it possible to detect, as asignal of I+J, a reproduction signal of which signal level changesfollowing change in light quantity of return light from the reproductiononly area. On the contrary, in the recordable/reproducible area, outputsignals of the light receiving surfaces I and J are caused to undergosubtractive operation, thereby making it possible to detect, as a signalof I-J, a reproduction signal of which signal level changes independency upon change of polarization plane of return light from therecordable/reproducible area.

Further, the optical pick-up 5 receives the remaining return light ofthe main beam by the central light receiving surfaces A˜D through amulti-lens 58 in which concave lens and cylindrical lens are combined.Then, the optical pick-up 5 adds output signals between light receivingsurfaces in the diagonal direction with respect to output signals of thelight receiving surfaces A˜D by applying the so-called astigmatismthereafter to implement subtractive processing thereto, thereby makingit possible to detect, as a signal of (A+C)-(B+D), a focus error signalFE of which signal level changes in dependency upon focus errorquantity.

Moreover, in the recordable/reproducible area, output signals are addedbetween light receiving surfaces corresponding to the circumferentialdirection of the optical disc 4 thereafter to implement subtractiveprocessing thereto between the added results, thereby making it possibleto detect, as a signal of (A+D)-(B+C), a wobble signal WB of whichsignal level changes in dependency upon meandering of pregrooves.

Further, in the recordable/reproducible area, output signals of theselight receiving surfaces A˜D are added, thereby making it possible todetect light quantity of main spot as a signal of A+B+C+D.

The optical pick-up 5 allows outputs by these respective light receivingsurfaces to undergo current-to-voltage conversion to output them. A RFamplifier 7 is formed (constituted) with an amplifier circuit of thematrix circuit configuration, and is operative to receive output signalsA˜D of these light receiving surfaces outputted from the optical pick-up5 to execute the above-described operational processing with respect tothe optical pick-up 5. At this time, the RF amplifier 7 switches theoperation mode in accordance with control data DC outputted from asystem controller 8.

In this embodiment, as the operation mode, the first operation modecorresponding to the reproduction only area and the second operationmode corresponding to the recordable/reproducible area are provided.

The RF amplifier 7 is operative in the first operation mode to addoutput signals by respective light receiving surfaces I, J to generate areproduction signal RF (I+J), and is operative in the second operationmode to allow output signals of the light receiving surfaces I and J toundergo subtractive operation to generate a reproduction signal RF(I-J). Further, the RF amplifier 7 amplifies this reproduction signal RFby the gain corresponding to each area thereafter to binarize it by thespecified slice level to output a binary signal S1.

Namely, the RF amplifier 7 comprises, as shown in FIG. 7, an operationalamplifier 71A for carrying out subtractive synthesis of output signalsby the respective light receiving surfaces I, J and an operationalamplifier 71B for carrying out additive synthesis thereof, and isadapted to carry out, by an operational amplifier 71c, switching betweena reproduction signal RF (I-J) obtained by the operational amplifier 71Aand a reproduction signal RF (I+J) obtained by the operational amplifier71B to output a reproduction signal thus obtained through an equalizer71D.

The respective operational amplifiers 71B, 71C are respectivelyswitching operational amplifiers, wherein when respective inputterminals S are S=0, each "1" side is enabled, and when they are S=1,each "2" side is enabled, whereby these operational amplifiers carry outoperational processing by gains different at the "1" side and the "2"side. Moreover, a mode switching (select) signal RFSWO such that S iscaused to be 0 (zero) in the first operation mode corresponding to thereproduction only area, and S is caused to be 1 in the second operationmode corresponding to the recordable/reproducible area is delivered tothe control input terminal S of the operational amplifier 71B. Further,a mode switching (select) signal RFSW1 such that S is caused to be 0(zero) in the first operation mode corresponding to the reproductiononly area and S is caused to be 1 in the second operation modecorresponding to the recordable/reproducible area is delivered to thecontrol input terminal S of the operational amplifier 71C. It is to benoted that this mode switching signal RFSW1 is adapted so that S iscaused to be 1 at the time of reproduction of the UTOC area.

Moreover, the RF amplifier 7 may implement subtractive operation tooutput signals by the respective light receiving surfaces E, F togenerate a tracking error signal TE (E-F) whereby when the operationmode is the first operation mode, it outputs this tracking error signalTE by the specified gain, while when the operation mode is the secondoperation mode, it switches the polarity of the tracking error signal TEto carry out switching so that the frequency is caused to be broader andthe gain is increased to more degree to output it.

Namely, the RF amplifier 7 comprises, as shown in FIG. 8, an operationalamplifier 72A for carrying out subtractive synthesis of output signalsby respective light receiving surfaces E, F and respective operationalamplifiers 72B, 72C supplied with a tracking error signal TE obtained bythe operational amplifier 72A.

The operational amplifier 72B is a switching operational amplifier inwhich the mode switching signal RFSWO is inputted to the control inputterminal S so that the "1" side and the "2" side are selectivelyoperative. This operational amplifier 72B is adapted so that when thecontrol input terminal S is S=0, the "1" side is enabled, and when thecontrol input terminal S is S=1, the "2" side is enabled to carry outoperation processing by gains different at the "1" side and the "2" sideto invert the polarity of the tracking error signal, and to switch(change) the frequency band and the gain.

Moreover, the operational amplifier 72C is a switching operationalamplifier in which the mode switching signal RFSW1 is inputted to thecontrol input terminal S so that the "1" side and the "2" side areselectively operative. This operational amplifier 72C is operative as aswitching circuit adapted so that when the control input terminal S isS=0, the "1" side is enabled to output a tracking error signal TEobtained by the operational amplifier 72A, and when the control inputterminal S is S=1, the "2" side is enabled to output a tracking errorsignal TE switched so that its polarity is inverted, and the frequencyband is broadened and the gain is increased by the operational amplifier72B.

Further, the RF amplifier 7 includes means for generating a focus errorsignal FE ((A+C)-(B+D)) and a wobble signal WB ((A+D)-(B+C)) from outputsignals of the central light receiving surfaces A˜D to output them.

Further, the RF amplifier 7 comprises, as shown in FIG. 9, anoperational amplifier 73A for carrying out additive synthesis of outputsignals of the light receiving surfaces A˜D, and an operationalamplifier 73B supplied with an added signal (A+C+B+D) obtained from theoperational amplifier 73A. The operational amplifier 73B is a switchingoperational amplifier in which the mode switching signal RFSW1 isinputted to the control input terminal S so that the "1" side and the"2" side are selectively operative. This operational amplifier 73B isadapted so that when the control input terminal S is S=0, the "1" sideis enabled, it is operative as merely voltage follower, and when theinput terminal S is S=1, the "2" side is enabled so that it functions asa low-pass filter. Further, the RF amplifier 7 is operative in thesecond operation mode to generate, from a tracking error signal TE inwhich its polarity is inverted, and the frequency band and the gain areswitched, a traverse signal TR of which signal level changes at a periodwhere laser beams traverse the pregrooves to output it. On the contrary,the RF amplifier 7 is operative in the first operation mode tosequentially compare peak hold results and bottom hold results of thereproduction signal RF to thereby generate a mirror signal of whichsignal level changes at a period where laser beams traverse pits toswitch the band limiting frequency to output this mirror signal as atraverse signal TR. Thus, the traverse signal TR is caused to undergoswitching relating to the generating method, the gain and the band independency upon the first and second operation modes.

Thus, the RF amplifier 7 is adapted to switch the operation processingmethod, the gain and the frequency characteristic in dependency uponcontrol data DC to output various signals necessary in carrying outrecording/reproduction of respective areas of the optical disc 4.

The servo circuit 9 receives tracking error signal TE and focus errorsignal FE from the RF amplifier 7 to move, in left and right directionsand in upper and lower directions, the object lens 6 in dependency uponthe tracking error signal TE and the focus error signal FE to therebyconduct the tracking control and the focus control.

Further, the servo circuit 9 switches the operation (mode) in dependencyupon the control data DC outputted from the system controller 8 togenerate a clock (clock signal) from the reproduction signal RF or thewobble signal WB. In addition, the servo circuit 9 controls a spindledriver 10 so that clocks (clock signals) generated in this wayrespectively have specified frequencies to drive the spindle motor 3 tothereby drive the optical disc 4 under the condition of constant linearvelocity by the spindle servo in which meandering of progrooves or theformation period of pits is caused to be reference.

Moreover, the servo circuit 9 outputs a control signal to the opticalpick-up 5 on the basis of light quantity detection result of laser beamsseparately (independently) obtained from the optical pick-up 5 tothereby set light quantity of laser beams to a specified (predetermined)light quantity in correspondence with the area of the laser beamirradiation position, and in correspondence with the operation at thetime of reproduction, and the operation at the time of recording.

Further, the servo circuit 9 drives a sled motor 11 comprised of d.c.motor to allow the optical pick-up 5 to undergo seek operation. At thistime, the servo circuit 9 loads target value outputted from the systemcontroller 8 into counter included therewithin thereafter tosequentially down-count count value of this counter by the traversesignal TR inputted from the RF amplifier 7 to control the sled motor 11so that it is stopped when the count value becomes equal to (value)zero.

An address decoder 12 frequency-demodulates the wobble signal WB incarrying out recording/reproduction of the area of pregrooves to detectposition information ATIP of the laser beam irradiation position fromthe demodulation result to output it.

A digital signal processing circuit 13 sequentially latches binarysignals S1 with the clock (clock signal) generated by the servo circuit9 being as reference to thereby convert the binary signals S1 intoserial data. Further, the digital signal processing circuit 13 encodesthis serial data thereafter to execute digital signal processing such aserror correction processing, etc. to thereby reproduce data recorded onthe optical disc 4 to output it to the host computer 2 as occasiondemands.

In reproducing, in this way, data recorded on the optical disc 4, withrespect to the lead-in area and the UTOC area, the digital signalprocessing circuit 13 outputs, to the system controller 8, managementinformation and/or position information, etc. obtained from thereproduction result through bus to store them into a memory 19. Thus, inthis optical disc apparatus 20, by the system controller 8, managementof data recorded in the program area and the unrecorded (not yetrecorded) area of the program area can be carried out, and the boundaryposition between the start position of the recordable/reproducible areawhere pregrooves are provided, i.e., the recordable/reproducible areaand the reproduction only area by pits can be detected.

Moreover, address data is detected from the reproduction data to outputthis address data to the system controller 8, thereby making it possibleto detect address data of the laser beam irradiation position by thesystem controller 8.

On the contrary, the digital signal processing circuit 13 is operativeso that in the case where the area of pregroove is recorded, it addserror correction code, etc. to input data D1 inputted from the hostcomputer 2 to convert it so that specified (predetermined) datastructure is provided thereafter to carry out Eight to FourteenModulation (EFM) thereof. Further, the digital signal processing circuit13 outputs, to a driver 14, the modulated data thus obtained at aspecific (predetermined) timing with the position information ATIP beingas reference to drive the modulation coil M by the driver 14.

Thus, the optical disc apparatus 20 is adapted to apply modulationmagnetic field by the input data D1 to the laser beam irradiationposition to thermally magnetically record the input data D1.

Here, in the case where reproduction signal RF (I+J) is detected in thefirst operation mode, the level difference between peak signal obtainedby peak-holding the reproduction signal RF and the bottom signalobtained by bottom-holding the reproduction RF becomes large by pits inthe reproduction only area.

On the other hand, since no pit exist in the recordable/reproduciblearea, the level difference between the peak signal obtained bypeak-holding the reproduction signal RF and the bottom signal obtainedby bottom-holding the reproduction signal RF does not become large. Inview of this, a judgment circuit 15 detects whether the level differencebetween the peak signal and the bottom signal of the reproduction signalRF (I+J) is larger or smaller than a predetermined reference level valueset in advance to thereby judge whether corresponding area is thereproduction only area including pits or the recordable/reproduciblearea including pregrooves.

In this example, in generating a binary signal from the reproductionsignal RF, the reproduction signal RF is integrated to generate slicereference level to compare the slice reference level and thereproduction signal RF to generate a binary signal. Namely, in theoptical disc 4 of this kind, also with respect to the reproduction onlyarea by pits, predetermined data is recorded by EFM. In this EFM, in thecase where the d.c. level after modulation is held at the 0 level sothat the RF amplifier 7 is held at setting corresponding to the area ofthe laser beam irradiation position, the integrated result of thereproduction signal RF becomes in correspondence with the slice level ingenerating the binary signal S1 in the RF amplifier 7.

The system controller 8 is formed (constituted) by microcomputer forcontrolling the operation of the entirety of the optical disc apparatus20 to execute the processing procedure shown in FIGS. 10 and 11 tothereby rotationally drive the optical disc 4 thereafter to allow theoptical pick-up 5 to undergo seek operation in response to controlcommand outputted from the host computer 2.

Namely, processing operation by the system controller 8 shifts from stepSP1 to step SP2 when power is turned ON to wait for loading of theoptical disc 4. When the optical disc 4 is loaded, the processingoperation by the system controller 8 shifts to step SP3 to control theservo circuit 9 to carry out starting of the spindle motor 3 to therebyrotationally drive the optical disc 4 at a specified (predetermined)rotation velocity.

Subsequently, the processing operation by the system controller 8 shiftsto step SP4 to output control data DC to the servo circuit 9 to move theoptical pick-up 5 into the lead-in area to set the operation mode of theRF amplifier 7 to the first operation mode corresponding to the area ofpits thereafter to drive the servo circuit 9 to execute processing offocus search to subsequently start the focus control and the trackingcontrol. Thus, in the servo circuit 9, the tracking control and thefocus control can be carried out by the reproduction systemcorresponding to the area of pits. The system controller 8 reproducesmanagement information (TOC) recorded in the lead-in area in this stateto store it into the memory included therewithin from the digital signalprocessing circuit 13.

Thus, the system controller 8 discriminates kind (type) of the loadedoptical disc 4 from the management information stored in this memory,whereby in the case where this optical disc 4 is the reproduction onlyoptical disc, the system controller 8 waits for command of the hostcomputer 2 to execute reproduction processing with the managementinformation recorded in this memory being as reference.

On the contrary, in the case where the loaded optical disc 4 is theoptical disc for recording/reproduction, or the hybrid disc, theprocessing operation by the system controller 8 subsequently shifts tostep SP5 to read out start address of the UTOC area from the managementinformation stored in the memory to calculate start address with respectto the boundary between pits and pregrooves by this start address.

In this embodiment, the optical disc 4 is adapted so that the areacorresponding to 3 clusters of the lead-in area side from the startaddress of the UTOC area is set to start address of this boundary. Thesystem controller 8 subtracts address corresponding to 3 clusters fromthe start address to calculate start address of the boundary to storethis calculation result into the memory.

Subsequently, the processing by the system controller 8 shifts to stepSP6 to wait for input of seek command from the host computer 2. When theseek command is inputted, the processing operation by the systemcontroller 8 shifts to step SP7. At this step, the system controller 8detects address data of the laser beam irradiation position through thedigital signal processing circuit 13 to thereby detect current positionof the optical pick-up 5.

Subsequently, the processing operation by the system controller 8 shiftsto step SP8, at which whether or not the optical pick-up 5 passes acrossthe boundary during seek operation. This judgment is executed (carriedout) by judging whether or not the start address of the UTOC area existwithin the range from the address of the current position detected atthe step SP7 up to the target address designated by the seek command.When negation result is obtained, the processing operation by the systemcontroller 8 shifts to step SP9.

In this case, the system controller 8 subtracts the target address fromaddress of current position while maintaining the RF amplifier 7 in theoperation mode set at present to set count value up to the seek targetat the counter of the servo circuit 9 by the subtraction result.Subsequently, the system controller 8 controls the servo circuit 9 tostart seek operation.

The system controller 8 waits for completion of the seek operation bythe servo circuit 9. When the seek operation is completed, theprocessing operation by the system controller 8 shifts to step S10 tocontrol the servo circuit 9 to carry out the focus control, the trackingcontrol and the spindle control. Namely, the rotation number of thespindle motor is caused to be in correspondence with the target rotationnumber by the spindle control, light beams are caused to be convergedwithin the depth of focal point (focus) of light beams by the focuscontrol, and the main spot of light beam is caused to be in the statewhere it traces the track center by the tracking control. Afterrespective servo controls are completed, address of the laser beamirradiation position is detected by the digital signal processingcircuit 13. Then, the system controller 8 allows the entirety of thesystem to carry out starting of seek operation as occasion demands tocarry out various servo controls so that the optical pick-up 5 islocated at the target position designated by the seek command.

Further, the processing operation by the system controller 8subsequently shifts to step SP16 to control the digital signalprocessing circuit 13, etc. in accordance with the write-in/read-outcommand inputted from the host computer 2 along with the seek command torecord data from the host computer 2 at the target position, or toreproduce data from the target position to output it to the hostcomputer 2. The processing operation returns to the step SP6 to wait forinput of subsequent seek command.

Thus, in this optical disc apparatus 20, in the case where (light spotof) the optical pick-up 5 does not pass across the boundary, an approachis employed to detect movement quantity of the optical pick-up 5 withthe traverse signal TR being as reference while maintaining the RFamplifier 7 to have the characteristic set at present to allow theoptical pick-up 5 to undergo seek operation up to the target position.

On the contrary, in the case where the optical pick-up 5 passes acrossthe boundary during seek operation, the affirmative result is obtainedat the step SP8. Thus, the processing operation by the system controller8 shifts to step SP11. At this step, the system controller 8 subtractsstart address of the boundary from address of current position to setthe counter of the servo circuit 9 by the subtraction result. Thus, thesystem controller 8 set, as the target, the area of 3 clusters of thelead-in area side from the boundary start address, i.e., start addressof the UTOC area to subsequently control the servo circuit 9 to startseek operation.

Subsequently, the system controller 8 waits for completion of seekoperation by the servo circuit 9. When the seek operation is completed,the processing operation by the system controller 8 shifts to step S12to control the servo circuit 9 to start the tracking control and thefocus control. Subsequently, when ON state of the focus servo isdetected by the servo circuit 9, the system controller 8 allows thejudgment circuit 15 to detect (judge) whether the area where the opticalpick-up 5 exists at present is the reproduction only area or therecordable/reproducible area.

Further, the system controller 8 sets, on the basis of the judgmentresult, the operation mode of the RF amplifier 7 and the operation ofthe servo circuit 9 so as to become in correspondence with the areawhere laser beams are irradiated to thereby set the operation of theentirety so as to correspond to the reproduction technique of the laserbeam irradiation position thereafter to shift to the execution of theprocessing operation at step SP13. At this step, when ON state of thetracking servo is detected, the system controller 8 detects address dataof the laser beam irradiation position by the digital signal processingcircuit 13. Subsequently, the processing operation by the systemcontroller 8 shifts to step SP14, at which whether or not the opticalpick-up 5 crosses over the boundary, i.e., whether or not any boundaryexists within the range until the remaining ultimate seek target. Thus,when the judgment result that the optical pick-up 5 has crossed over theboundary, the processing operation by the system controller 8 shifts tostep SP9.

Thus, the system controller 8 allows the optical pick-up 5 to undergoseek operation up to the remaining target address while maintaining theoperation mode of the RF amplifier 7 and the operation of the servocircuit 9 in the state set at present. Thereafter, the processingoperation by the system controller 8 shifts to step ST10.

Namely, there are instances where if the distance of seek operation islong, or the like when seek operation is carried out in this way, seekoperation may be conducted in the state beyond the boundary by inertiaof the optical pick-up 5, etc. although seek operation is carried outwith the lead-in area side by three sectors from the start address ofthe UTOC area being as the target. In such a case, judgment of the areaof the laser beam irradiation position is made at the step SP12 in thestate where movement of the optical pick-up 5 is stopped, thereby makingit possible to simply and securely confirm the area of the laser beamirradiation position.

After setting of the operations of the RF amplifier 7 and the servocircuit 9 is subsequently carried out on the basis of theabove-mentioned judgment result, the remaining seek operation isexecuted, thus making it possible to securely carry out seek operationto the target position in the state where unstable operation of theservo circuit is effectively avoided. Moreover, after the seekoperation, switching of the operation mode of the RF amplifier 7 iscarried out to make a setting such that the tracking error signal TE,etc. is also caused to correspond to the area to execute the remainingseek operation, thereby making it possible to quickly form the state ofthe so-called just tracking after the seek operation. Thus, the accesstime can be shortened.

Moreover, at this time, switching of the operation of the servo circuit9 is carried out along with the above-mentioned switching operation toimmediately control the rotational speed (velocity) of the optical disc4 in correspondence with the area where the optical pick-up 5 exists atpresent (i.e., in a manner to constitute control system of spindle servowith meandering of pregrooves or the formation period of pits being asreference), thereby making it possible to start recording/reproductionoperation in a short time after the seek operation.

On the contrary, in the case where any boundary still exists in the areaup to the ultimate seek target, the processing operation by the systemcontroller 8 shifts to step SP15 as the result of the fact that thenegation result is obtained at the step SP14.

At this step, the system controller 8 calculates the remaining addressrequired until the optical pick-up 5 crosses over the boundary by thestart address of the boundary and the address of the current position toadd a predetermined value to the remaining address. Thus, the systemcontroller 8 calculates the necessary minimum remaining address quantitysuch that the optical pick-up 5 can securely cross over the boundary.Further, the system controller 8 controls the servo circuit 9 whilemeasuring the time corresponding to the address quantity by timerincluded therewithin to allow the optical pick-up 5 to carry out trackjump.

Thus, the system controller 8 allows the optical pick-up 5 to carry outtrack jump at the necessary minimum quantity such that the opticalpick-up 5 can securely cross over the boundary. Thereafter, theprocessing operation by the system controller 8 returns to the stepSP12. Namely, in the case where track jump is carried out across theboundary, it becomes difficult to correctly detect a traverse signalserving as reference in the course of the jump. For this reason, if anapproach is employed to once interrupt the seek operation in front ofthe boundary thereafter to carry out track jump within the necessaryminimum range by the reference except for the traverse signal, it ispossible to safely and securely carry out track jump across theboundary.

Accordingly, if switching of the operations of the RF amplifier 7 andthe servo circuit 9 is carried out after track jump is conducted in thisway to execute the remaining seek operation, seek operation to thetarget position can be securely carried out in the state where unstableoperation of the servo circuit is effectively avoided. Thus, in thisembodiment, there is employed the simple configuration in which d.c.motor is applied to the sled motor 11 and the position detecting sensorof the optical pick-up 5 is omitted, thereby making it possible tostably and securely carry out access operation.

Meanwhile, when management of the track jump quantity is carried out bythe time in this way, there are instances where track jump may not becorrectly carried out across the boundary. In view of this, in thisembodiment, an approach is employed to return from the step SP15 to thestep SP12 to confirm, for a second time, the area of the laser beamirradiation position by the judgment circuit 15 thereafter to detectaddress of the current position at the step SP13 to repeat theprocessing operations from the step SP14 to the step SP15 as occasiondemands.

Thus, in this optical apparatus 20, in connection with the case wherethe optical pick-up 5 passes across the boundary between the lead-inarea and the UTOC area in the optical disc for recording/reproduction,and the case where it passes across the boundary between the programarea of the inner circumferential side and the UTOC area in the hybridoptical disc, an approach is employed to execute the subsequent seekprocessing with traverse signals corresponding to the reproductionsystems of respective areas being as the reference after the opticalpick-up 5 has securely crossed over the boundary, thereby making itpossible to securely carry out seek operation to the target position.

In the above-mentioned configuration, the optical disc apparatus 20rotationally drives the optical disc 4 under the condition of constantlinear velocity by the spindle motor 3 to reproduce data recorded on theoptical disc 4 on the basis of return light of laser beam emitted fromthe optical pick-up 5 in the above-mentioned state, or to drive themodulation coil M to record desired data by the thermal magneticrecording technique.

In this recording/reproduction operation, the optical disc apparatus 20drives the sled motor 11 comprised of d.c. motor in accordance with theseek command from the host computer 2 to drive the optical pick-up 5 andthe modulation coil M to reproduce data from a desiredrecording/reproduction position, or to record data.

In this seek, and recording/reproduction processing, the optical discapparatus 20 discriminates kind (type) of the loaded optical disc 4 bymanagement information recorded in the lead-in area to carry outswitching between reproduction systems in correspondence with respectiveoptical discs 4, and to carry out switching of seek operation.

Namely, in the case where the optical disc 4 is the reproduction onlyoptical disc, in the optical disc apparatus 20, the operation mode ofthe RF amplifier 7 is set to the first operation mode corresponding tothe area of pits, and the operation (mode) of the servo circuit 9 is setso to carry out the spindle servo with the pit formation period being asreference. Thus, in this case, in the optical disc apparatus 20, data isreproduced from a reproduction signal RF of which signal level changesin dependency upon change in the light quantity of return light.Moreover, the tracking control and the focus control are conducted bythe tracking error signal and the focus error signal corresponding tothe reproduction signal RF. Further, seek processing is executed withthe traverse signal corresponding to the reproduction signal RF being asreference.

On the contrary, in the case where the optical disc 4 is the opticaldisc for recording/reproduction or the hybrid optical disc, the opticaldisc apparatus 20 can judge the area of pits and the area of pregrooveswith the start address of the UTOC area obtained from the lead-in areabeing as reference. Thus, the operation mode of the RF amplifier 7 andthe operation of the servo circuit 9 are set, thereby making it possibleto execute recording/reproduction processing in correspondence with thereproduction systems of respective areas.

On the other hand, when seek command is inputted, whether or not theoptical pick-up 5 passes across the boundary is first judged in theoptical disc apparatus 20, whereby when it does not pass across theboundary, the seek processing is directly executed up to the targetposition in the state where the operation mode of the RF amplifier 7 andthe operation of the servo circuit 9 are maintained as they are.

In the case where it is judged that the optical pick-up 5 passes acrossthe boundary, the seek processing is once executed with the position infront of the boundary being as target in the optical disc apparatus 20,whereby run-away, etc. of the optical pick-up 5 during seek operationcan be effectively avoided. In the case where the optical pick-up 5 hascrossed over the boundary during the seek operation, the operation modeof the RF amplifier 7 and the operation of the servo circuit 9 areswitched. After the remaining seek quantity is confirmed, the seekprocessing is executed up to the ultimate target position. Thus, theseek processing is executed up to the remaining ultimate target positionby the traverse signal corresponding to the reproduction system of thearea beyond the boundary. As a result, seek operation up to the targetposition can be securely carried out.

At this time, since the operation mode of the RF amplifier 7 is switchednot only to switch the generating method, the gain and the band of thetraverse signal, but also to switch the polarity, the frequency band andthe gain of the tracking error signal, and the generating method of thereproduction signal RF, and the operation of the servo circuit 9 isswitched, it is possible to quickly start the recording/reproductionoperation after seek operation.

On the contrary, when seek operation can be correctly carried out up tothe position in front of the boundary in the seek operation with theposition in front of the boundary being as the seek target, necessaryminimum track jump sufficient to cross over the boundary is executedwith the time being as reference in place of the traverse signal. Thus,run-away, etc. of the optical pick-up 5 during seek operation can beeffectively avoided.

Subsequently, in this optical disc apparatus 20, after track jump isrepeated as occasion demands, the operation mode of the RF amplifier 7and the operation of the servo circuit 9 are switched. After theremaining seek quantity is confirmed, the seek processing is executed upto the ultimate target position. Thus, the seek processing is executedup to the remaining ultimate target position by the traverse signalcorresponding to the reproduction system of the area beyond theboundary. As a result, seek operation can be securely carried out up tothe target position.

In accordance with the above-mentioned configuration, approach isemployed to carry out seek operation with 3 clusters of the lead-in areaside being as target from the start address of the UTOC area recorded inthe lead-in area thereafter to securely cross over the boundary tosubsequently carry out seek operation up to the ultimate targetposition, thereby making it possible to safely and securely carry outseek operation by the simple configuration.

(2) Second embodiment

FIG. 12 is a block diagram showing an optical disc apparatus accordingto the second embodiment. This optical disc apparatus 20 is adapted tohave an ability to selectively load three kinds (types) of optical discssimilarly to the optical disc apparatus according to the firstembodiment. It is to be noted that, in the configuration shown in FIG.12, components common to those of the configuration of FIG. 1 arerespectively designated by the same reference numerals, and therepetitive explanation will be omitted.

In this optical disc apparatus 20, the judgment circuit 15 in theabove-described first embodiment is omitted to thereby simplify theentire configuration, and to execute the processing procedure shown inFIG. 13 in a system controller 21 to thereby shorten the time requiredfor seek operation. It is to be noted that since, in the processingprocedure of the system controller 21, the processing procedure from thetime point when power is turned ON until address of current position isdetected in response to the seek command is the same as theabove-described processing procedure in FIG. 10, the processing stepssubsequent from FIG. 9 are respectively designated by correspondingreference numerals, and the repetitive explanation is omitted.

Namely, when power is turned ON and the optical disc 4 is loaded, thesystem controller 21 starts the spindle motor 3 to rotationally drivethe optical disc 4 at a specified (predetermined) rotation speed(velocity) to reproduce management information from the lead-in area bythe reproduction system corresponding to the area of pits todiscriminate kind (type) of the optical disc 4. In the case where thisoptical disc 4 is the reproduction only optical disc, the systemcontroller 21 waits for command from the host computer 2 in the statewhere management information reproduced from the lead-in area is storedinto the memory included therewithin.

On the contrary, in the case where the loaded optical disc 4 is theoptical disc for recording/reproduction, or the hybrid optical disc,start address of the UTOC area is read out from the managementinformation stored in the memory to wait for command from the hostcomputer 2 in that state.

After the same processing procedure as the first embodiment is executed,the processing operation by the system controller 21 shifts to step SP26shown in FIG. 13 to wait for input of seek command from the hostcomputer 2. When the seek command is inputted, the processing by thesystem controller 21 shifts to step SP27. At this step, the systemcontroller 21 detects address data of the laser beam irradiationposition through digital signal processing circuit 13 to thereby detectcurrent position of the optical pick-up 5.

The processing operation by the system controller 21 then shifts to stepS28 to judge whether or not the optical pick-up 5 passes across theboundary by the address of the current position and the start address ofthe UTOC area. As a result, when negation result is obtained, theprocessing operation by the system controller 21 shifts to step SP29 tosubtract target address from address of the current position whilemaintaining the RF amplifier 7 to have the operation mode set at presentto set count value up to the seek target at the counter of the servocircuit 9 by the subtraction result. Subsequently, the system controller21 controls the servo circuit 9 to start seek operation.

The system controller 21 waits for completion of the seek operation bythe servo circuit 9, whereby when the seek operation is completed, theprocessing operation by the system controller 21 shifts to step SP30 tocontrol the servo circuit 9 to carry out the focus control, the trackingcontrol and the spindle control. Namely, the rotation number (the numberof rotations) of the spindle motor is caused to be in correspondencewith the target rotation number by the spindle control, light beams arecaused to be converged within the depth of focal point (focus) by thefocus control, and the main spot of light beam is caused to be in thestate where it traces the track center by the tracking control. Afterrespective servo controls are completed, address of the laser beamirradiation position is detected by the digital signal processingcircuit 13. Thus, the system controller 8 allow the entirety of thesystem to carry out starting of the seek operation for a second time asoccasion demands to carry out various servo controls of the opticalpick-up 5 so that it is located at the target position designated by theseek command.

Further, the processing operation by the system controller 21subsequently shifts to step SP36 to control the digital signalprocessing circuit 13, etc. in accordance with the write-in and read-outcommand inputted from the host computer 2 along with the seek command torecord data from the host computer 2 at the target position, or toreproduce data from the target position to output it to the hostcomputer 2 to return to the step SP26 to wait for input of thesubsequent seek command.

In the optical disc apparatus 20, in the case where the optical pick-up5 does not pass across the boundary during seek operation, movementquantity of the optical pick-up 5 is detected with the traverse signalTR being as reference while maintaining the RF amplifier 7 to have thecharacteristic set at present to allow the optical pick-up 5 to undergoseek operation up to the target position.

On the contrary, in the case where the optical pick-up 5 passes acrossthe boundary during seek operation, since the affirmative result isobtained at step S28, the processing operation by the system controller21 shifts to step SP31. At this step, the system controller 21 subtractsstart address of the UTOC area from address of the current position tocalculate, from the subtraction result, traverse count value Nch up tothe boundary.

Further, the system controller 21 calculates the traverse count valuefrom the boundary up to the ultimate target to set count value at theservo circuit 9. Subsequently, the processing operation by the systemcontroller 21 shifts to step SP32 to control the servo circuit 9 tostart the seek operation at a stroke up to the ultimate target. At thistime, the system controller 21 makes a setting such that the traversesignal TR is not counted with respect to the servo circuit 9.

When the seek operation is started in this way, the processing operationby the system controller 21 shifts to step SP33 to up-count the traversesignal TR by the counter included therewithin to shift to step S34 tojudge whether or not this count value Ntk is in correspondence with thetraverse count value Nch up to the boundary to thereby judge whether ornot the optical pick-up 5 has reached the boundary. As a result, whenthe negation result is obtained, the processing operation by the systemcontroller 21 returns to the step SP33.

Thus, the system controller 21 repeats the processing procedure of stepsSP33-SP34-SP35 to predict the timing at which (light spot of) theoptical pick-up 5 traverses the boundary by the count value of thetraverse signal by the counter included therewithin.

When the optical pick-up 5 reaches the boundary, the affirmative resultis obtained at step SP34. Thus, the processing operation by the systemcontroller 21 shifts to step SP35 to switch the operation mode of the RFamplifier 7 and the operation of the servo circuit 9 so as to become incorrespondence with the succeeding area. Further, the system controller21 allows the servo circuit 9 to start count operation of the traversesignal TR, whereby after the optical pick-up 5 crosses over theboundary, seek operation is carried out by the servo circuit 9 such thatthe optical pick-up 5 is located at the ultimate target position. Theprocessing operation by the system controller 21 then shifts to stepSP30.

Thus, the optical disc apparatus 20 can carry out seek operation at astroke up to the ultimate target. As a result, the time required for theseek operation can be shortened to more degree as compared to the firstembodiment.

Further, at this time, an approach is employed to predict the boundaryto switch the operation mode of the RF amplifier 7 and the operation ofthe servo circuit 9 to thereby effectively avoid unstable operation ofthe servo circuit even after the optical pick-up 5 crosses over theboundary, thus making it possible to securely carry out seek operationto the target position. In addition, after seek operation, the operationof the servo circuit 9 and the operation mode of the tracking errorsignal TE, etc. are switched so as to become in correspondence with thearea after seek operation. Thus, it is possible to quickly formrecordable/reproducible state. Also by such an approach, the access timecan be shortened.

In accordance with the configuration shown in FIG. 12, such an approachis employed to predict, by the counter included therewithin, the timingat which the optical pick-up 5 reaches the boundary with the startaddress of the UTOC area recorded in the lead-in area being as referenceto carry out switching of the operation by the predictive result tocarry out seek operation at a stroke up to the ultimate target position,thereby making it possible to obtain the advantages similar to those ofthe first embodiment by simpler configuration as compared to the firstembodiment, and to shorten the time required for the seek operation.

(3) Other embodiments

It should be noted that while start address of the UTOC area (U-TOCstart address) included in the management information TOC recorded inthe lead-in area is used as information indicating the boundary betweenthe reproduction only area and the recordable/reproducible area in theabove-described embodiments, the management information TOC may berecorded in the area except for the lead-in area on the optical disc 4.

For example, in the case where a memory 101 in which the managementinformation TOC is stored is provided at a cartridge 100 within whichthe optical disc 4 is accommodated, a management information readingsection 110 for reading out the management information TOC from thememory 101 is provided at the disc unit side to deliver the managementinformation TOC which has been read by the management informationreading section 110 to the system controller 21.

Moreover, while it has been described that the reproduction signal isintegrated to judge whether or not the reproduction system employed isthe reproduction system corresponding to the laser beam irradiationposition, this invention is not limited to such approach, but can widelyapply to various judgment methods, as occasions demand, e.g., a methodin which judgment is made by reproduced address.

Further, while it has been described that seek operation is once carriedout, with the area of 3 clusters of the lead-in area side from the startaddress of the UTOC area being as target, this invention is not limitedto such seek system, but seek operation may be once carried out with thelead-out side from the start address of the UTOC area being as target.

Further, e.g., an approach may be employed to predict, on the basis ofstart address of the UTOC area (U-TOC start address) included in themanagement information TOC which has been read out from the lead-in areaof the reproduction only area, whether the portion designated as theseek destination is the reproduction only area or therecordable/reproducible area to carry out seek operation thereafter toswitch setting on the basis of the prediction.

Further, while it has been described that the traverse signal isgenerated by the tracking error signal or from the reproduction signal,this invention is not limited to such traverse signal generating method,but can be widely applied to the case where the traverse signal isgenerated from sum signal of signals from four light receiving surfacesA˜D arranged at the center.

Further, while it has been described that optical pick-up by the lightreceiving element in which light receiving surfaces are disposed inupper and lower directions and in left and right directions with respectto the central light receiving surface is used to apply the astigmatismand the three-spot method to generate the focus error signal and/or thetracking error signal, etc., this invention is not limited to such anapproach, but can be widely applied to the case where optical pick-upelements of various forms are used. In addition, while it has beendescribed that this invention is applied to the optical disc apparatusto which the optical disc in which the information recording surface isdivided into the reproduction only area by pits and therecordable/reproducible area including pregrooves is applied, thisinvention is not limited to such optical disc apparatus, but can bewidely applied to the case where reproduction and/or recording ofvarious optical discs, such as, for example, optical disc in which thearea is divided into the reproduction only area by pits and therecordable/reproducible area by sample servo are carried out.

We claim:
 1. A disc apparatus adapted for accessing a disc-shapedrecording medium including recording tracks in a spiral form or in aconcentrical form, the recording medium being such that the area thereonis divided, every predetermined position in a radial direction, into atleast one reproduction only area and one recordable area, and thatboundary recording track position information indicating a boundaryrecording track position between the reproduction only area and therecordable area which are adjacent to each other is recorded,theapparatus comprising:a head for providing an access to the disc-shapedrecording medium; head movement means for moving the head in the radialdirection of the disc-shaped recording medium; current positiondetecting means for detecting a recording track position that the headis accessing at present to output current position informationindicating the current recording track position; means for detecting thenumber of movement recording tracks, which is operative to detect, onthe basis of target recording track position information indicating atarget recording track position, the current position information andthe boundary recording track position information, the number ofmovement recording tracks from the current recording track position upto the boundary recording track position when the boundary recordingtrack position indicated by the boundary recording track positioninformation exists between the current recording track positionindicated by the current position information and the target recordingtrack position indicated by the target recording track positioninformation; traverse signal generating means operative to generate,from a reproduction signal obtained by the head, a traverse signal ofwhich signal level changes every time the head traverses the recordingtracks at a first setting corresponding to the reproduction only area ora second setting corresponding to the recordable area selected on thebasis of a switching signal when the head is being moved by the headmovement means; count means for counting, on the basis of the traversesignal, the number of recording tracks over which the head has beenmoved; and switching signal generating means for outputting theswitching signal to the traverse signal generating means on the basis ofthe number of movement recording tracks detected by the means fordetecting the number of movement recording tracks and the number ofrecording tracks counted by the count means.
 2. A disc apparatus as setforth in claim 1,wherein the head includes light beam irradiation meansfor irradiating light beams onto the disc-shaped recording medium andplural detectors for detecting rays of reflected light from thedisc-shaped recording medium, and wherein the traverse signal generatingmeans includes operation processing means for performing an operationwith respect to output signals of the plural detectors by a firstoperational expression corresponding to the reproduction only area or asecond operational expression corresponding to the recordable areaselected on the basis of the switching signal.
 3. A disc apparatus asset forth in claim 1,wherein the head includes light beam irradiationmeans for irradiating light beams onto the disc-shaped recording medium,and wherein the traverse signal generating means includes amplifyingmeans for amplifying an output signal of the head by a first gaincorresponding to the reproduction only area or a second gaincorresponding to the recordable area selected on the basis of theswitching signal.
 4. A disc apparatus as set forth in claim 1,whereinthe head includes light beam irradiation means for irradiating lightbeams onto the disc-shaped recording medium, and wherein the traversesignal generating means includes band limiting means for limiting bandof an output signal of the head at a first frequency band correspondingto the reproduction only area or a second frequency band correspondingto the recordable area selected on the basis of the switching signal. 5.A disc apparatus as set forth in claim 1,wherein the boundary recordingtrack position information is recorded on the recording track of thedisc-shaped recording medium, and wherein the recording track where theboundary recording track position information is recorded is accessed bythe head to read out the boundary recording track position information.6. A disc apparatus as set forth in claim 1,wherein the disc apparatusis adapted to access the disc-shaped recording medium accommodatedwithin a cartridge provided with memory means in which the boundaryrecording track position information is stored, the disc apparatusfurther comprising read-out means for reading out the boundary recordingtrack position information from the memory means.
 7. A disc apparatus asset forth in claim 2,wherein the operation processing means performs anoperation with respect to output signals of the plural detectors by afirst operational expression for generating a reproduction signal fromthe reproduction only area comprised of an area in which the recordingtracks are formed by pits or a second operational expression forgenerating a tracking error signal from the recordable area comprised ofan area in which the recording tracks are formed by grooves.
 8. A discapparatus as set forth in claim 3,wherein the amplifying means is suchthat the first gain is smaller than the second gain.
 9. A disc apparatusas set forth in claim 4,wherein the band limiting means is such that thefirst frequency band is narrower than the second frequency band.
 10. Adisc apparatus as set forth in claim 1,wherein the switching signaloutput means is adapted so that when the number of movement recordingtracks detected by the means for detecting the number of movement tracksand the number of recording tracks counted by the count means are incorrespondence with each other, it outputs the switching signal to thetraverse signal generating means.
 11. A disc apparatus adapted foraccessing a disc-shaped recording medium including recording tracks in aspiral form or in a concentrical form, the recording medium being suchthat the area thereon is divided, every predetermined position in aradial direction, into at least one reproduction only area and onerecordable area, and that boundary recording track position informationindicating a boundary recording track position between the reproductiononly area and the recordable area which are adjacent to each other isrecorded,the apparatus comprising:a head for providing an access to thedisc-shaped recording medium; head movement means for moving the head inthe radial direction of the disc-shaped recording medium; currentposition detecting means for detecting a recording track position thatthe head is accessing at present to output current position informationindicating the current recording track position; boundary detectingmeans for detecting, on the basis of target recording track positioninformation indicating a target recording track position, the currentposition information and the boundary recording track positioninformation, whether or not the boundary recording track positionindicated by the boundary recording track position information existsbetween the current recording track position indicated by the currentposition information and the target recording track position indicatedby the target recording track position information; means for detectingthe number of movement recording tracks, which is operative so that whenit is detected by the boundary detecting means that the boundaryrecording track position exists, the detecting means detects the numberof movement recording tracks from the current recording track positionup to a recording track position spaced by a predetermined number ofrecording tracks from the boundary recording track position; traversesignal generating means operative to generate, from a reproductionsignal obtained by the head, a traverse signal of which signal levelchanges every time the head traverses the recording tracks at a firstsetting corresponding to the reproduction only area or a second settingcorresponding to the recordable area selected on the basis of aswitching signal when the head is being moved by the head movementmeans; count means for counting, on the basis of the traverse signal,the number of recording tracks over which the head has been moved; areadetecting means for detecting, on the basis of a reproduction signalobtained by the head, whether an area where the head is positioned isthe reproduction only area or the recordable area; and control means forcarrying out a first operation to move the head toward the boundaryrecording track position by the head movement means, whereby when thenumber of recording tracks counted by the count means becomes incorrespondence with the number of movement recording tracks detected bythe means for detecting the number of movement recording tracks, thecontrol means stops movement of the head by the head movement means tooutput, to the traverse signal generating means, the switching signalcorresponding to an area detection signal by the area detecting means inthe state where the head is stopped.
 12. A disc apparatus as set forthin claim 11,wherein the control means detects, on the basis of the areadetection signal by the area detecting means, subsequently to the firstoperation, whether or not the head reaches the boundary recording trackposition, whereby when the head does not reach the boundary recordingtrack position, the control means further moves the head by the headmovement means by the time determined on the basis of current positioninformation obtained by the current position detecting means and thetarget recording track position information.
 13. A disc apparatus as setforth in claim 11,wherein the head includes light beam irradiation meansfor irradiating light beams onto the disc-shaped recording medium, andplural detectors for detecting rays of reflected light from thedisc-shaped recording medium, and wherein the traverse signal generatingmeans performs an operation with respect to output signals of the pluraldetectors by a first operational expression corresponding to thereproduction only area or a second operational expression correspondingto the recordable area selected on the basis of the switching signal.14. A disc apparatus as set forth in claim 11,wherein the head includeslight beam irradiation means for irradiating light beams onto thedisc-shaped recording medium, and wherein the traverse signal generatingmeans includes amplifying means for amplifying an output signal of thehead by a first gain corresponding to the reproduction only area or asecond gain corresponding to the recordable area selected on the basisof the switching signal.
 15. A disc apparatus as set forth in claim11,wherein the head includes light beam irradiation means forirradiating light beams onto the disc-shaped recording medium, andwherein the traverse signal generating means includes band limitingmeans for limiting band of an output signal of the head at a firstfrequency band corresponding to the reproduction only area or a secondfrequency band corresponding to the recordable area selected on thebasis of the switching signal.
 16. A disc apparatus as set forth inclaim 11,wherein the boundary recording track position information isrecorded on the recording track of the disc-shaped recording medium, andwherein the recording track where the boundary recording track positioninformation is recorded is accessed by the head to read out the boundaryrecording track position information.
 17. A disc apparatus as set forthin claim 11,wherein the disc apparatus is adapted to access thedisc-shaped recording medium accommodated within a cartridge providedwith memory means in which the boundary recording track positioninformation is stored, the disc apparatus further comprising read-outmeans for reading out the boundary recording track position informationfrom the memory means.
 18. A disc apparatus as set forth in claim13,wherein the operation processing means performs an operation withrespect to output signals of the plural detectors by a first operationalexpression for generating a reproduction signal from the reproductiononly area comprised of an area where the recording tracks are formed bypits or a second operational expression for generating a tracking errorsignal from the recordable area comprised of an area where the recordingtracks are formed by grooves.
 19. A disc apparatus as set forth in claim14,wherein the gain amplifying means is such that the first gain issmaller than the second gain.
 20. A disc apparatus as set forth in claim15,wherein the band limiting means is such that the first frequency bandis narrower than the second frequency band.
 21. A disc access method foraccessing, by moving a head in a radial direction of a disc-shapedrecording medium, the disc-shaped recording medium including recordingtracks in a spiral form or in a concentrical form, the recording mediumbeing such that the area thereon is divided, every position in theradial direction thereof, into at least one reproduction only area andone recordable area, and that boundary recording track positioninformation indicating a boundary recording track position between thereproduction only area and the recordable area which are adjacent toeach other is recorded,the method comprising the steps of:reading theboundary recording track position information recorded on thedisc-shaped recording medium; detecting a current recording trackposition that the head is accessing at present; detecting, on the basisof the detected current recording track position, a target recordingtrack position and the boundary recording track position indicated bythe boundary recording track position information, the number ofmovement recording tracks from the current recording track position upto the boundary recording track position when the boundary recordingtrack position exists between the current recording track position andthe target recording track position; generating, from a reproductionsignal obtained by the head, a traverse signal of which signal levelchanges every time the head traverses the recording tracks at a firstsetting corresponding to the reproduction only area or a second settingcorresponding to the recordable area selected on the basis of aswitching signal when the head is being moved; counting, on the basis ofthe traverse signal, the number of recording tracks over which the headhas been moved; and outputting the switching signal on the basis of thenumber of movement recording tracks and the counted number of recordingtracks.
 22. A disc access method as set forth in claim 21,wherein whenthe number of movement recording tracks and the counted number ofrecording tracks are in correspondence with each other, the switchingsignal is outputted to the traverse signal generating means.
 23. A discaccess method for accessing, by moving in a radial direction of adisc-shaped recording medium, the disc-shaped recording medium includingrecording tracks in a spiral form or in a concentrical form, therecording medium being such that the area thereon is divided, everyposition in the radial direction thereof, into at least one reproductiononly area and one recordable area, and that boundary recording trackposition information indicating a boundary recording track positionbetween the reproduction only area and the recordable area which areadjacent to each other is recorded,the method comprising the stepsof:reading the boundary recording track position information recorded onthe disc-shaped recording medium; detecting a current recording trackposition that the head is accessing at present; detecting, on the basisof the detected current recording track position, a target recordingtrack position and the boundary recording track position indicated bythe boundary recording track position information, the number ofmovement recording tracks from the current recording track position upto a recording track position spaced by a predetermined number ofrecording tracks from the boundary recording track position when theboundary recording track position exists between the current recordingtrack position and the target recording track position; generating, froma reproduction signal obtained by the head, a traverse signal of whichsignal level changes every time the head traverses the recording tracksat a first setting corresponding to the reproduction only area or asecond setting corresponding to the recordable area selected on thebasis of a switching signal when the head is being moved; moving thehead toward the boundary recording track position; counting, on thebasis of the traverse signal, the number of recording tracks over whichthe head has been moved; stopping movement of the head when the countednumber of recording tracks becomes in correspondence with the detectednumber of movement recording tracks; detecting, on the basis of areproduction signal by the head, in the state where the head is stopped,whether an area where the head is positioned is the reproduction onlyarea or the recordable area; and outputting the switching signal inaccordance with the detection result thus obtained.